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Content archived on 2022-12-23

Small-x Physics: Interface between perturbative and non-perturbative QCD dynamics.

Objective

The aim of the project is an investigation in a framework of the Quantum Chromodynamics of phenomena in a transitional region between "hard" and "soft" processes. Special theoretical methods will be developed for this purpose. These methods will be verified in high-energy interactions induced by leptons and hadrons. Special attention will be to the small-x region.

The OCD perturbation theory will be extensively used for a study of a broad class of phenomena in hard processes. A region of applicability of this theory and a role of nonperturbative effects will be studied, using the topological expansion, method of vacuum correlators and strings model. In the small-x region the effective Regge theory will be applied. The collaboration involves scientific groups, which proposed and developed the abovementioned approaches.

The new aspects of this project are:

a) Investigation of the perturbative (BFKL) dynamics in the small-x region, including NLO results for both trajectory of the Pomeron and impact factors. Developments of new methods of analysis of perturbative diagrams in OCD and its supersymmetric extensions;
b) A unified approach to both structure functions and diffractive production, which include both single Pomeron exchange and unitarization effects;
c) A study of an interplay between perturbative and nonperturbative dynamics for spin-dependent structure functions;
d) Analysis of amplitudes with quark exchanges in the multi-Regge kinematics and predictions for spectra and wave functions of qq states.

The research activities will proceed in the following general directions:

- perturbative effects in the small-x physics;
- phenomenological analysis of small-x deep inelastic scattering and other diffractive processes;
- spin effects and polarized structure functions;
- mesonic Regge-trajectories in QCD;
- glueballs and nonperturbative effect for the Pomeron.

The main results of the project are expected to be:

- new theoretical methods of analysis of processes in the transitional region between "soft" and "hard" processes;
- application of these methods to analysis of structure functions of hadrons and diffractive processes;
- understanding of a role of noperturbative effects for high energy interactions of leptons and hadrons;
- formulation of predictions for future super colliders.

The aim of the project is an investigation in a framework of the Quantum Chromodynamics of phenomena in a transitional region between "hard" and "soft" processes. Special theoretical methods will be developed for this purpose. These methods will be verified in high-energy interactions induced by leptons and hadrons. Special attention will be to the small-x region.

The OCD perturbation theory will be extensively used for a study of a broad class of phenomena in hard processes. A region of applicability of this theory and a role of nonperturbative effects will be studied, using the topological expansion, method of vacuum correlators and strings model. In the small-x region the effective Regge theory will be applied. The collaboration involves scientific groups, which proposed and developed the abovementioned approaches.

The new aspects of this project are:

a) Investigation of the perturbative (BFKL) dynamics in the small-x region, including NLO results for both trajectory of the Pomeron and impact factors. Developments of new methods of analysis of perturbative diagrams in OCD and its supersymmetric extensions;
b) A unified approach to both structure functions and diffractive production, which include both single Pomeron exchange and unitarization effects;
c) A study of an interplay between perturbative and nonperturbative dynamics for spin-dependent structure functions;
d) Analysis of amplitudes with quark exchanges in the multi-Regge kinematics and predictions for spectra and wave functions of qq states.

The research activities will proceed in the following general directions:

- perturbative effects in the small-x physics;
- phenomenological analysis of small-x deep inelastic scattering and other diffractive processes;
- spin effects and polarized structure functions;
- mesonic Regge-trajectories in QCD;
- glueballs and nonperturbative effect for the Pomeron.

The main results of the project are expected to be:

- new theoretical methods of analysis of processes in the transitional region between "soft" and "hard" processes;
- application of these methods to analysis of structure functions of hadrons and diffractive processes;
- understanding of a role of noperturbative effects for high energy interactions of leptons and hadrons;
- formulation of predictions for future super colliders.

Call for proposal

Data not available

Funding Scheme

Data not available

Coordinator

Dipartimento di Fisica, Universita` Milano-Bicocca, Italy
EU contribution
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Address
Piazza della Scienza 3
20126 Milano
Italy

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Total cost
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Participants (7)